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Research paper
Impact of tobacco prices and smoke-free policy on smoking cessation, by gender and educational group: Spain, 1993–2012 Enrique Regidor a,b,c,*, Cruz Pascual a,c, Carolina Gira´ldez-Garcı´a a,c, Silvia Galindo a, David Martı´nez a,c, Anton E. Kunst d a
Department of Preventive Medicine and Public Health, Universidad Complutense de Madrid, Madrid, Spain CIBER Epidemiologı´a y Salud Pu´blica (CIBERESP), Madrid, Spain Instituto de Investigacio´n Sanitaria del Hospital Clı´nico San Carlos (IdISSC), Spain d Department of Public Health, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands b c
A R T I C L E I N F O
A B S T R A C T
Article history: Received 10 March 2015 Received in revised form 25 May 2015 Accepted 26 May 2015
Background: To evaluate the effect of tobacco prices and the implementation of smoke-free legislation on smoking cessation in Spain, by educational level, across the period 1993–2012. Methods: National Health Surveys data for the above two decades were used to calculate smoking cessation in people aged 25–64 years. The relationship between tobacco prices and smoking quit-ratio was estimated using multiple linear regression adjusted for time and the presence of smoke-free legislation. The immediate as well as the longer-term impact of the 2006 smoke-free law on quit-ratio was estimated using segmented linear regression analysis. The analyses were performed separately in men and women with high and low education, respectively. Results: No relationship was observed between tobacco prices and smoking quit-ratio, except in women having a low educational level, among whom a rise in price was associated with a decrease in quit-ratio. The smoke-free law altered the smoking quit-ratio in the short term and altered also pre-existing trends. Smoking quit-ratio increased immediately after the ban – though this increase was significant only among women with a low educational level – and then decreased in subsequent years except among men with a high educational level. Conclusion: A clear relationship between tobacco prices and smoking quit-ratio was not observed in a recent period. After the implementation of smoke-free legislation the trend in the quit ratio in most of the socio-economic groups was different from the trend observed before implementation, so existing inequalities in smoking quit-ratio were not widened or narrowed. ß 2015 Elsevier B.V. All rights reserved.
Keywords: Tobacco prices Smoke-free legislation Smoking cessation Educational level Spain
Introduction Tobacco control policies, especially when implemented as part of a comprehensive programme, can significantly reduce tobacco use. Raising the price of tobacco by increasing taxes and introducing clean indoor air laws by prohibiting smoking in public places have been singled out as the most effective measures for reducing overall smoking rates (IARC, 2011). In high-income countries, smoking is persistently associated with social disadvantage, with the result that reducing social inequalities in smoking has become a political priority in many
* Corresponding author at: Department of Preventive Medicine and Public Health, Universidad Complutense de Madrid, Faculty of Medicine, Ciudad Universitaria, 28040 Madrid, Spain. Tel.: +34 913941521; fax: +34 913941803. E-mail address: [email protected] (E. Regidor).
places. There is, however, no guarantee that interventions known to reduce overall smoking behaviour will be equally effective across all socio-economic groups. Although there are sufficient data to show that an increase in price reduces tobacco consumption (Becker, Grossman, & Murphy, 1994; Gallus, Schiaffino, La Vecchia, Townsend, & Fernandez, 2006), decreases the prevalence of adult tobacco use (Farrelly, Bray, Pechacek, & Woolery, 2001; Kinh, Ross, Levy, Minh, & Ngoc, 2006) and increases the likelihood of smoking cessation (Chaloupka & Warner, 2000; Forster & Jones, 2001), existing evidence of a possibly different price effect on different socio-economic groups is less conclusive. Whereas most studies have found that tobacco use among lower-income populations and persons of low socio-economic position is more responsive to price (Brown, Platt, & Amos, 2014; Hill, Amos, Clifford, Platt, & Amos, 2014; Thomas et al., 2008), some studies have failed to observe any differences (Franks et al., 2007; Wasserman, Manning, Newhouse, & Winkler, 1991) and other
http://dx.doi.org/10.1016/j.drugpo.2015.05.011 0955-3959/ß 2015 Elsevier B.V. All rights reserved.
Please cite this article in press as: Regidor, E., et al. Impact of tobacco prices and smoke-free policy on smoking cessation, by gender and educational group: Spain, 1993–2012. International Journal of Drug Policy (2015), http://dx.doi.org/10.1016/j.drugpo.2015.05.011
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studies suggest that persons with a higher educational level may be more sensitive to tobacco prices either because they get a significant reduction in cigarette consumption (Lee, Hwang, Ye, & Chen, 2004) or because they are more motivated to quit smoking (Ringel & Evans, 2001). Evidence of the effect of clean indoor air laws on smoking behaviour is less plentiful. A reduction in smoking behaviours has been observed among workers subject to restrictions in the workplace (Fichtenberg & Glantz, 2002; IARC, 2009). At a population level, the effect of clean indoor air regulations on smoking behaviour is similar in all studies, when it comes to shortterm assessment (Brugha et al., 2009; Callinan, Clarke, Doherty, & Kelleher, 2010; Lee, Glantz, & Millett, 2011; Regidor et al., 2011); in the long term, however, pre-existing trends in smoking are affected according to some studies (Brugha et al., 2009; Regidor et al., 2011) and remain unaltered according to others (Callinan et al., 2010; Lee et al., 2011). As regards inequalities in smoking, there is weak evidence to show that workplace smoking restrictions may be more effective for higher educational groups, but at a population level the effect of clean indoor air laws on smoking cessation does not vary with socio-economic position (Brown et al., 2014; Hill et al., 2014), though only a small number of studies have been undertaken. With the aim of increasing the amount of empirical evidence, this study assessed the effect of both types of smoking-control measures in smoking cessation in different socio-economic groups in Spain. The first regulation in Spain that sought to control smoking through taxation was introduced in 1992, since when tobacco prices have risen considerably. In addition, Spain promulgated the 2006 Smokefree Act, thus becoming one of the first European countries to implement this type of measure which banned smoking in workplaces, bars and restaurants. The impact of nationwide tobacco control policies on smoking behaviour should preferably be examined in a longitudinal study design, wherein information about smoking behaviour before and after the implementation of a policy is measured. Unfortunately, longitudinal data on smoking are rare. In most of the cases alternative approaches are used to obtain evidence on the potential impact of national policies on smoking. For example, the use of estimates on smoking behaviour based on crosssectional studies of several years. A natural experiment was thus undertaken, using data on smoking drawn from a series of national interview surveys conducted over the course of the two decades since 1992. Specifically, the aim of this study was to evaluate the effect of tobacco prices and the implementation of smoke-free legislation on the smoking cessation, by educational level, across the period 1993–2012. Methods The data were drawn from eight Spanish National Health Surveys conducted over the course of the preceding twenty years, i.e., 1993, 1995, 1997, 2001, 2003–2004, 2006–2007, 2009–2010, and 2011–2012. Subjects were selected by means of a stratified multi-stage sampling strategy and information was collected through personal interviews at subjects’ homes. A more detailed outline of the methodology used in these surveys can be found elsewhere (MSSSI, 2015). The sampling framework was made up of the Spanish non-institutionalised population aged 16 or over. First the towns were chosen by random selection proportional to the size of the population, and then the census areas households in each section were chosen by simple random selection. Individual households were subsequently selected by simple random selection, and one adult aged 16 or over was selected in each household. Information on tobacco consumption was included in the questionnaire. Specifically, in answer to the item, ‘‘Could you
please state whether you smoke’’, interviewees were asked to choose one of the following possible replies: (1) Yes, I smoke daily; (2) Yes, I smoke, though not daily; (3) No, I do not smoke but I used to; or, (4) No, I do not smoke now and have never routinely smoked. For study purposes, we only included subjects who were smokers, daily and non-daily, or ex-smokers at the date of the interview. The smoking cessation quit-ratio was defined as the ratio of former smokers to ever smokers. Educational level was used as the indicator of socio-economic position: this variable referred to the highest level of education attained and was grouped into the following two categories: lower secondary education or less; and upper secondary education or higher. The quit-ratio estimates were computed for the group aged 25–64 years. The age of 25 years was chosen as the lower limit because persons of this age would most likely have attained their highest level of education. Similarly, the age of 64 years was chosen as the upper limit to avoid imprecise estimates in women aged over 64 years because, until 2003, less than 5% of Spanish women in this age group had smoked at some time in their lives. The annual trend in tobacco prices in Spain for the period 1993– 2012 was obtained from the consumer price index, published by the National Institute of Statistics (Instituto Nacional de Estadı´stica, 2014). In order to use the real price of tobacco, the annual tobacco prices were adjusted for inflation. The quit ratio was the indicator of smoking cessation used. This measure is frequently used to assess progress of comprehensive tobacco control programs, as in the United States where the ratio of former smokers to ever smokers for each survey year is obtained (Agaku, King, & Dube, 2014). Nevertheless, changes in quit ratio can be driven by population changes other than cessation (e.g., differing mortality rates among current/former smokers). The present analysis has been limited to the adult population aged 25– 64 years, therefore it has been excluded the possibility of mortality bias among older smokers. The age-standardised quit ratio was estimated for each study period, taking the 1993 ever-smoker population as standard. By using the method of direct standardization, in each educational level the age-specific quit ratios were weighted by standard population in each age. Although eight National Health Surveys were analysed, the quit ratios were calculated for 12 periods. The interviews in the first four National Health Surveys were conducted over a period of two weeks, and so a single quit-ratio estimate was computed for 1993, 1995, 1997 and 2001, respectively. However, since the interviews in the last four National Health Surveys were distributed over twelve months, i.e., from April of one year to March of the next (2003–2004 and 2009–2010) or from July of one year to June of the next (2006– 2007 and 2011–2012), in each of these cases, we computed two quit-ratio estimates: one based on the interviews conducted in the first six months; and another based on the interviews conducted in the last six months. We thus obtained eight estimates deemed to correspond to the years 2003, 2004, 2006, 2007, 2009, 2010, 2011 and 2012, respectively. Separate analyses of regression were performed for men and women. Given the change in survey duration (2 weeks versus 12 months), the measurements in the period after 2003–2004 will be characterized by greater error variance and perhaps correlation between the error terms of neighbouring time points. The Durbin– Watson statistic for serial autocorrelation of the error terms in the regression models was calculated (Wagner, Soumerai, Zhang, & Ross-Degnan, 2002). No evidence of autocorrelation was detected because values were closed to 2. In each category of educational level, the relationship between tobacco prices and the quit ratio was analysed using linear regression. Because of that relationship may be a reflection of the smoking epidemic, the analysis was adjusted for time as it has been
Please cite this article in press as: Regidor, E., et al. Impact of tobacco prices and smoke-free policy on smoking cessation, by gender and educational group: Spain, 1993–2012. International Journal of Drug Policy (2015), http://dx.doi.org/10.1016/j.drugpo.2015.05.011
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done in other previous studies (Agaku et al., 2014; Bosdriesz, Willemsen, Stronks, & Kunst, 2015). In view of the fact that previous studies in Spain and in Ireland reported that smoking trends had changed substantially after the introduction of smokefree legislation (Brugha et al., 2009; Regidor et al., 2011), this relationship was addressed in two ways: firstly, by focusing on the period preceding the introduction of comprehensive smoke-free legislation in January 2006; and secondly, the relationship between tobacco prices and the quit ratio was calculated for the entire study period, adjusted for trend and the presence or absence of the law. To reflect the absence or presence of the law, we created a dichotomous variable whose value was 0 in the years preceding the implementation of the Smoke-free Act and 1 in 2006 and subsequent years. The introduction of smoke-free legislation was then evaluated. A segmented regression analysis was performed to assess whether there had been a change in quit-ratio levels and/or trends between the pre- and post-intervention periods. Segmented regression analysis is a quasi-experimental approach for evaluating longitudinal effects of interventions (Sanson-Fisher, D’Este, Carey, Noble, & Paul, 2013; Wagner et al., 2002). The analysis involves fittings an interrupted time series to the data. A time series is fit pre- and postintervention using a disjointed segmented linear regression model. Each segment of the series is allowed to exhibit both level and a trend. Segmented regression analysis makes it possible to estimate changes in level and trend associated with the intervention, controlling for baseline level and trend. A change in level, e.g. a jump or drop in the outcome after the intervention, constitutes an abrupt intervention effect. A change in trend is defined by an increase or decrease in the slope of segment after the intervention as compared with the segment preceding the intervention. The model used was the next: QRt ¼ b0 þ b1 time þ b2 intervention þ b3 time after intervention þ et ; where QRt is the quit ratio in year t; time is a continuous variable indicating time in any year at time t from the start of the study period; intervention is an indicator of time t occurring before (intervention = 0) or after (intervention = 1) the introduction of smoke-free legislation; and time after intervention is a continuous variable that counts the number of years after the intervention at time t, denoted 0 for the period preceding the introduction of smokefree legislation. In the model, b0 estimates the baseline level of the outcome, the quit ratio, at time zero; b1 estimates changes in the quit ratio that occurred in each year before the intervention (i.e., the baseline trend); b2 estimates changes in the quit-ratio level that
3
occurred immediately after the intervention, i.e., from the end of the preceding segment; and b3 estimates post- versus pre-intervention changes in trend in the quit ratio. The error term et at time t represents random variability not explained by the model. Finally, the effect of smoke-free legislation was also estimated by the elaboration of a counterfactual scenario to answer the question: what would have been the value of the quit ratio at the end of the study period in the absence of intervention? To do this, apart from calculating the predicted value of the ratio quit in 2012 using the model based on intervention, the predicted value was also calculated using the model based on baseline level and time only, as if the intervention had not occurred (counterfactual scenario). Results The trend in tobacco prices and the absence or presence of a smoke-free law in the study period can be seen in Table 1. From 1993 to 2003 tobacco price increased by 50% and in the two decades covered by this study, the price multiplied by 2.5. Table 1 also shows the sample size along with the quit ratio in men and women at each of the observation points. The trend in tobacco prices and that of the quit ratios in subjects having low and high educational levels are shown in Fig. 1. The relationship between tobacco prices and the quit ratio is shown in Table 2. In the period prior to the implementation of smoke-free legislation, no significant relationship was observed between tobacco prices and the quit ratio in either of the two categories of educational level after adjusting for time. When the entire study period was analysed, no significant relationship was in evidence, except among women with a low educational level. In this group, the increase in tobacco prices was associated with a fall in the quit ratio (regression coefficient: 0.089; p = 0.002). The results of the assessment of the impact of the smoke-free law on the quit ratio can be seen in Table 3 and Fig. 2. Before the law’s introduction, the quit ratio displayed an upward trend in both men and women with low and high educational levels. The b1 coefficient of the baseline trend was significant in all four groups. Following the introduction of the law, the quit ratio increased in all groups, though the magnitude of this increase was greater in women than in men. The coefficient that measured the change in quit-ratio level after the intervention as compared with the quit-ratio level preceding the intervention only was statistically significant in women with a low educational level (b2 = 4.66; p < 0.001). After the law’s introduction, a change was observed in the trend among men with a low educational level and women in both educational groups. The regression coefficient was significant in men (b3 = 0.79; p = 0.023) and in women (b3 = 0.83; p = 0.009) with a low educational level;
Table 1 Tobacco price index, absence or presence of smoke free-law, and number of smokers and former smokers in the sample and quit ratio in men and women by year. Spain 1993– 2012. Year
Tobacco prix index
Smoke-free law
Sample size of smokers and former smokers (n) and quit ratio (%) and standard error (SE) Women
Men
1993 1995 1997 2001 2003 2004 2006 2007 2009 2010 2011 2012
100.0 112.2 132.8 143.0 151.8 156.7 158.2 167.1 186.2 210.4 230.9 241.8
No No No No No No Yes Yes Yes Yes Yes Yes
n
Quit ratio
SE
n
Quit ratio
SE
4840 1451 1450 4719 2409 2256 3761 2961 2547 2252 2288 2105
26.4 29.2 29.7 31.4 34.3 34.4 38.6 39.5 37.5 38.9 39.2 41.9
0.6 1.2 1.2 0.7 1.0 1.0 0.8 0.9 1.0 1.0 1.0 1.1
2262 774 853 3058 1548 1639 2547 2017 1849 1732 1720 1555
23.3 22.7 24.6 27.6 32.8 31.1 36.8 37.6 36.0 41.5 36.5 36.4
0.9 1.5 1.5 0.8 1.2 1.1 1.0 1.1 1.1 1.2 1.2 1.2
Please cite this article in press as: Regidor, E., et al. Impact of tobacco prices and smoke-free policy on smoking cessation, by gender and educational group: Spain, 1993–2012. International Journal of Drug Policy (2015), http://dx.doi.org/10.1016/j.drugpo.2015.05.011
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4
Men
Women
50
50
300
35
100
10
50
Prices index
2007
2006
2005
2004
2003
2002
2001
2000
1999
1998
1997
1996
1995
1993
0
2012
2011
2010
2009
2008
2007
2006
2005
2004
2003
2002
2001
2000
1999
1998
1997
1996
1995
50
0
0
1994
Quit ratio Prices index
5
0
1993
100
15
2012
Quit ratio
5
150
1994
10
25 20
2011
15
200
2010
150
20
Low
30
2009
25
Quit ratio %
Low
30
Prices index
200
2008
35
250
High
40
Prices index
250
High
40
Quit ratio %
300
45
45
Fig. 1. Age-standardized quit ratios by educational level and sex and tobacco prices.
Table 2 Parameter estimates and p-values from regression models evaluating the effect the tobacco prix on quit ratio (%) in Spain for the period 1993–2004 and for the period 1993– 2012. Low education
Period 1993–2004 (adjusting for time) Beta for men Beta for Women Period 1993–2012 (adjusting for time and presence/absence of the law) Men Beta (adjusting for time) Beta (adjusting for time plus presence/absence of the law) Women Beta (adjusting for time) Beta (adjusting for time plus presence/absence of the law)
High education
Coefficient
p value
Coefficient
p value
0.056 0.050
0.492 0.680
0.081 0.069
0.506 0.824
0.060 0.060
0.093 0.116
0.004 0.001
0.923 0.982
0.094 0.089
0.004 0.002
0.106 0.106
0.099 0.123
Table 3 Parameter estimates and p-values from segmented regression models predicting annual quit ratio (%) in Spain for the period 1993–2012. Low education
High education
Coefficient
p-value
Coefficient
p-value
Men Intercept b0 Baseline trend b1 Level change after law b2 Trend change after law b3
22.76 0.71 1.93 0.79
0.000 0.001 0.264 0.023
27.42 0.67 1.40 0.02
0.000 0.007 0.540 0.956
Women Intercept b0 Baseline trend b1 Level change after law b2 Trend change after law b3
21.48 0.51 4.66 0.83
0.000 0.002 0.001 0.009
23.07 1.17 3.10 1.19
0.000 0.003 0.365 0.082
among women with a high educational level, it bordered on statistical significance (b3 = 1.19; p = 0.082). The sum of b1 coefficient of the baseline trend and b3 coefficient of trend change after law would be the actual value of the new trend in the postintervention segment. The new trend was no significant: in men and women with a low educational level the value was 0.08 (p = 0.880) and 0.32 (p = 0.230), and in men and women with a high educational level the value was 0.69 (p = 0.126) and 0.02 (p = 0.968), respectively. Table 4 shows that, based on the intervention, the predicted value of the quit ratio in 2012 is lower than it would be if the intervention had not occurred, except in men with a high educational level among whom both values display a similar magnitude.
Discussion Main findings Prior to the introduction of the smoke-free law, the tobacco prices and the magnitude of the quit ratios showed an upward trend, but there was no evidence of relationship between tobacco prices and quit ratios in any of the groups studied after adjusting for time. Analysis of the entire study period showed similar results, and even a decrease in the percentage of smokers quitting among women with a low educational level. The smoke-free law not only altered the smoking pattern in the short term, but also altered preexisting trends. Whereas quit ratios rose in all groups shortly after the ban, they declined in the following years, except among men
Please cite this article in press as: Regidor, E., et al. Impact of tobacco prices and smoke-free policy on smoking cessation, by gender and educational group: Spain, 1993–2012. International Journal of Drug Policy (2015), http://dx.doi.org/10.1016/j.drugpo.2015.05.011
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Fig. 2. Age-standardized quit ratios by educational level and sex. The triangles represent subjects with low education and the diamonds represent subjects with high education. The dashed line represents the estimated data based on the segmented regression analysis.
Table 4 Estimated values for the quit ratio in percentage (and standard error) in 2012 based on the intervention (segmented regression) and on the counterfactual value (baseline level and trend only). Spain for the period 1993–2012.
Men Yˆ2012 Yˆ2012
(with law) =
Women Yˆ2012 (with Yˆ2012
b0 + b1 * 20 + b2 * 1 + b3 * 7 b0 + b1 * 20
(without law) =
law) =
b0 + b1 * 20 + b2 * 1 + b3 * 7 b0 + b1 * 20
(without law) =
Low education
High education
33.3 (0.9)
42.3 (1.3)
35.1 (0.8)
42.3 (0.8)
30.5 (0.8)
41.1 (1.9)
32.5 (0.9)
43.8 (1.4)
with a high educational level. In the long term, the magnitude of the quit ratio was lower in the presence of the law than in the counterfactual scenario which postulated its absence, once again with the single exception of men with a high educational level. Comparison with other studies and possible explanations A considerable number of studies have found that tobacco prices display an independent association with decreased consumption among smokers (Chaloupka & Warner, 2000; IARC, 2011; Levy, Chaloupka, & Gitchell, 2004). There are fewer studies however that address the relationship between price and definitive smoking cessation. Although some studies on young adults report a relationship between an increase in price and an increase in quit attempts, there is less evidence to show that raising tobacco prices is successful in terms of maintaining smoking cessation (Rice, Godfrey, Slack, Sowden, & Worthy, 2009). There is still less evidence regarding the relationship between tobacco prices and smoking cessation by reference to ever smokers’ socio-economic position. A study undertaken in the Netherlands reported that exposure to a price increase was not significantly associated with increased odds of quit attempts or successful smoking cessation in any socio-economic group (Nagelhout et al., 2013). In the present study the tobacco price was not associated with smoking cessation in most of the groups analysed. Even, among women with a low educational level, the relationship observed for the entire study period was contrary to expectations, because the quit ratio, rather than rising, fell with the increase in the price. This finding is probably due to the change in smoking patterns caused by the introduction of the Smokefree Act, in view of the fact that, in the years preceding the
implementation of this law, no relationship had been observed between the price of tobacco and quit ratios in any of the four groups analysed. The increase in quit ratios observed in Spain in the period immediately following the introduction of smoke-free legislation has also been observed in Scotland (Fowkes, Stewart, Fowkes, Amos, & Price, 2008) and England (Hackshaw, McEwen, West, & Bauld, 2010). Neither of these studies found any evidence of a differential impact depending on the socio-economic position of smokers in this immediate period. In the Netherlands too, a small effect of smoke-free legislation on quit attempts was observed in the period immediately following the law’s implementation but there were no educational differences in such attempts (Nagelhout et al., 2013). Only one study, undertaken in Italy, where the smoking ban in public places was absolute, has assessed the short- and long-term impact of smoke-free legislation on smoking habit by reference to the socio-economic position of individuals (Federico, Mackenbach, Eikemo, & Kunst, 2012). As in Spain, a sudden increase in the quit ratio was observed following the law’s introduction, whereas the quit ratio fell as post-legislation. In the case of persons with a high educational level, however, long-term trends differed: in Italy, the quit ratio fell in men and rose in women, whereas in Spain it remained stable in men and fell in women. The Italian findings agree with our counterfactual scenario (i.e., without the presence of the smoke-free law) where, in the long term, the magnitude of the quit ratio would have been more favourable for most of the groups studied. It is unlikely that the observed decrease in the quit ratio in most of the groups, after the smoke-free law, came about as a consequence of more subjects taking up smoking. In view of the age range of the study population (25–64 years), this finding is fundamentally due to relapses of former smokers who resume smoking. The authors of the study conducted in Italy indicated a possible relaxation in complying with the ban in work and public places. Yet, the results regarding this law’s effectiveness in Spain suggest that this has not been the case. Moreover, a trend in smoking behaviour similar to that reported in Italy and Spain has also been observed in Ireland. Probably, after the implementation of smoke-free legislation many people decided to give up smoking, increasing the number of ex-smokers, but some months later some of these smokers who got quitting returned to smoking. Since smoking cessation coincided in many smokers as a result of the law, the relapse that occurs in some smokers in the months
Please cite this article in press as: Regidor, E., et al. Impact of tobacco prices and smoke-free policy on smoking cessation, by gender and educational group: Spain, 1993–2012. International Journal of Drug Policy (2015), http://dx.doi.org/10.1016/j.drugpo.2015.05.011
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following the quit, due to withdrawal syndrome, it is expected that also affects many individuals. In any case, it cannot be excluded that other developments have affected the long-term decrease in quit ratios in Spain, such as ‘‘ceiling effects’’ if incremental changes in quit ratios tend to be smaller at higher levels or the continuing economic crisis. Study strengths and limitations One of the largest effects of tobacco price increases is to reduce the initiation of smoking initiation among youth. However, in the present study smoking initiation was not studied because educational level was used and people lower than under 25 years of age have less likely of attaining their highest level of education as people older. In any case, although changes in smoking cessation are, in addition to changes in smoking initiation, one of the mechanisms through which the smoking epidemic evolves, some authors have pointed that in later stages of the smoking epidemic, quitting smoking can make important may contribute to differences in smoking prevalence (Schaap et al., 2008). Other measures of smoking behaviour also could have been used (attempts quit, cigarettes per day). However, the attempts quit do not appear properly collected in all health surveys and estimates on the number of cigarettes per day from surveys are imprecise. In fact, some authors and national and international institutions use sales figures for monitoring the number of consumed cigarettes (Ferna´ndez et al., 2004; MSSSI, 2014a). Based on representative samples of the Spanish population, 12 quit-ratio estimates were obtained across a period of two decades, making it possible to perform segmented regression analysis of interrupted time series to control for prior trends, and to study the dynamics of change in quit ratios following the introduction of smoke-free legislation. However the study actually has statistical low power due to the small number of observations. For example, the finding of no significant relationships of price with quit ratio in the period before the Smoke-free Act could be due to the low power. The relationship between the price and the consumption of tobacco in Spain has been evaluated in two studies that found that a rise in real price of tobacco is associated with a decrease in cigarette consumption and an increase in smoking cessation (Ferna´ndez et al., 2004; Lo´pez Nicola´s, 2004). These studies used, respectively, tobacco official sales for the period 1965–2000 (Ferna´ndez et al., 2004) and data from national health surveys from 1995 to 1997 (Lo´pez Nicola´s, 2004). Probably the different findings with respect to those obtained in the present study are due to the different variables of smoking behaviour used. While Ferna´ndez et al. (2004) investigated the annual per capita cigarette consumption, Lo´pez Nicola´s (2004) investigated the duration up to quitting. According some studies that have evaluated the price responsiveness by age, the tobacco use among young people fall more in response to a price increase than the tobacco use among older people (Levy et al., 2004; Thomas et al., 2008). In the present study we performed a sensitivity analysis by selecting only young adults 25–44 years and the findings were similar: lack of relationship between increase in tobacco prices and quit ratio in all groups, except among women with a low educational level. In this group the regression coefficient for the entire study period, adjusted for trend and the presence or absence of the law was 0.10 (p = 0.027). The strategy used in this study was to perform estimates into four groups based on sex and educational level. Segmented regression aggregates subject according those individual variables by time point but does not allow for control of other individuallevel covariates. Quit ratios were higher in unemployed than in
unemployed persons (MSSSI, 2014b). Although the decrease in the magnitude of the quit ratio after the introduction of the smoke-free law may possibly have been due to the rise in unemployment brought about by the 2008 economic crisis, when the quit ratio was analysed in employed and unemployed persons from 2006 to 2012, the trend in both groups were similar to those among all Spanish men and women, respectively (data not shown). The 2006 Smoke-free Act banned smoking in all public and workplaces, with some exceptions in hospitality venues (no ban on venues of less than 100 m2, and ‘‘smoking areas’’ were allowed in venues over 100 m2). In January 2011, a new law was enacted (Ley 42/2010, de 30 de diciembre). The new smoking law amended the previous law by banning smoking in all places that had formerly been deemed an exception. Even so, previous studies have shown that the 2006 Act was effective, in that its implementation was followed by a decrease in second-hand smoke exposure, both at the workplace and among non-smokers during leisure time (Sureda et al., 2014). Although the quit ratio is frequently used to assess tobacco control policies (Agaku et al., 2014; Bosdriesz et al., 2015; Federico et al., 2012), it is a proxy of cessation rate because does not take into account age at starting and time since quit smoking. Therefore, the quit ratio may not be adequate to evaluate the effect of price or any other policy instrument of tobacco control implemented in a year, as the quit ratio includes smokers who quit smoking before that year and remained non-smokers since. Under the assumption that the study population is the same source population before and after the intervention, the quit ratio is able to detect changes in smoking cessation over the two periods, but it not sensitive to the exact timing of the occurrence of change. Conclusion This study’s findings do not support a clear relationship between tobacco prices and quit ratio in national populations in the study period. Moreover, we found that after the implementation of smoke-free legislation in Spain the trend in the quit ratio in most of the socio-economic groups studied was different from the trend observed before implementation. In view of the fact that there was a difference between the trends observed for men and women with a high educational level, the law’s implementation cannot be said to have widened or narrowed existing inequalities in the quit ratio. The smoke-free policies benefit the lower socioeconomic groups by the intended effect of decreasing exposure to environmental tobacco smoke, but they do not seem to affect inequalities in smoking. Funding This work was carried out by the project ‘‘Tackling socioeconomic inequalities in smoking: learning from natural experiments by time trend analyses and cross-national comparison (SILNE)’’, which is funded by the European Commission, Directorate-General for Research and Innovation, under the FP7-Health-2011 program, with grant agreement 278273. Competing interests The authors declare that they have no conflicts of interest. References Agaku, I. T., King, B. A., & Dube, D. (2014). Current cigarette smoking among adults – United States, 2005–2012. Mortality and Morbidity Weekly Report, 63, 29–34. Becker, G. S., Grossman, M., & Murphy, K. M. (1994). An empirical analysis of cigarette addiction. American Economic Review, 84, 396–418.
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Research paper
Impact of tobacco prices and smoke-free policy on smoking cessation, by gender and educational group: Spain, 1993–2012 Enrique Regidor a,b,c,*, Cruz Pascual a,c, Carolina Gira´ldez-Garcı´a a,c, Silvia Galindo a, David Martı´nez a,c, Anton E. Kunst d a
Department of Preventive Medicine and Public Health, Universidad Complutense de Madrid, Madrid, Spain CIBER Epidemiologı´a y Salud Pu´blica (CIBERESP), Madrid, Spain Instituto de Investigacio´n Sanitaria del Hospital Clı´nico San Carlos (IdISSC), Spain d Department of Public Health, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands b c
A R T I C L E I N F O
A B S T R A C T
Article history: Received 10 March 2015 Received in revised form 25 May 2015 Accepted 26 May 2015
Background: To evaluate the effect of tobacco prices and the implementation of smoke-free legislation on smoking cessation in Spain, by educational level, across the period 1993–2012. Methods: National Health Surveys data for the above two decades were used to calculate smoking cessation in people aged 25–64 years. The relationship between tobacco prices and smoking quit-ratio was estimated using multiple linear regression adjusted for time and the presence of smoke-free legislation. The immediate as well as the longer-term impact of the 2006 smoke-free law on quit-ratio was estimated using segmented linear regression analysis. The analyses were performed separately in men and women with high and low education, respectively. Results: No relationship was observed between tobacco prices and smoking quit-ratio, except in women having a low educational level, among whom a rise in price was associated with a decrease in quit-ratio. The smoke-free law altered the smoking quit-ratio in the short term and altered also pre-existing trends. Smoking quit-ratio increased immediately after the ban – though this increase was significant only among women with a low educational level – and then decreased in subsequent years except among men with a high educational level. Conclusion: A clear relationship between tobacco prices and smoking quit-ratio was not observed in a recent period. After the implementation of smoke-free legislation the trend in the quit ratio in most of the socio-economic groups was different from the trend observed before implementation, so existing inequalities in smoking quit-ratio were not widened or narrowed. ß 2015 Elsevier B.V. All rights reserved.
Keywords: Tobacco prices Smoke-free legislation Smoking cessation Educational level Spain
Introduction Tobacco control policies, especially when implemented as part of a comprehensive programme, can significantly reduce tobacco use. Raising the price of tobacco by increasing taxes and introducing clean indoor air laws by prohibiting smoking in public places have been singled out as the most effective measures for reducing overall smoking rates (IARC, 2011). In high-income countries, smoking is persistently associated with social disadvantage, with the result that reducing social inequalities in smoking has become a political priority in many
* Corresponding author at: Department of Preventive Medicine and Public Health, Universidad Complutense de Madrid, Faculty of Medicine, Ciudad Universitaria, 28040 Madrid, Spain. Tel.: +34 913941521; fax: +34 913941803. E-mail address: [email protected] (E. Regidor).
places. There is, however, no guarantee that interventions known to reduce overall smoking behaviour will be equally effective across all socio-economic groups. Although there are sufficient data to show that an increase in price reduces tobacco consumption (Becker, Grossman, & Murphy, 1994; Gallus, Schiaffino, La Vecchia, Townsend, & Fernandez, 2006), decreases the prevalence of adult tobacco use (Farrelly, Bray, Pechacek, & Woolery, 2001; Kinh, Ross, Levy, Minh, & Ngoc, 2006) and increases the likelihood of smoking cessation (Chaloupka & Warner, 2000; Forster & Jones, 2001), existing evidence of a possibly different price effect on different socio-economic groups is less conclusive. Whereas most studies have found that tobacco use among lower-income populations and persons of low socio-economic position is more responsive to price (Brown, Platt, & Amos, 2014; Hill, Amos, Clifford, Platt, & Amos, 2014; Thomas et al., 2008), some studies have failed to observe any differences (Franks et al., 2007; Wasserman, Manning, Newhouse, & Winkler, 1991) and other
http://dx.doi.org/10.1016/j.drugpo.2015.05.011 0955-3959/ß 2015 Elsevier B.V. All rights reserved.
Please cite this article in press as: Regidor, E., et al. Impact of tobacco prices and smoke-free policy on smoking cessation, by gender and educational group: Spain, 1993–2012. International Journal of Drug Policy (2015), http://dx.doi.org/10.1016/j.drugpo.2015.05.011
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studies suggest that persons with a higher educational level may be more sensitive to tobacco prices either because they get a significant reduction in cigarette consumption (Lee, Hwang, Ye, & Chen, 2004) or because they are more motivated to quit smoking (Ringel & Evans, 2001). Evidence of the effect of clean indoor air laws on smoking behaviour is less plentiful. A reduction in smoking behaviours has been observed among workers subject to restrictions in the workplace (Fichtenberg & Glantz, 2002; IARC, 2009). At a population level, the effect of clean indoor air regulations on smoking behaviour is similar in all studies, when it comes to shortterm assessment (Brugha et al., 2009; Callinan, Clarke, Doherty, & Kelleher, 2010; Lee, Glantz, & Millett, 2011; Regidor et al., 2011); in the long term, however, pre-existing trends in smoking are affected according to some studies (Brugha et al., 2009; Regidor et al., 2011) and remain unaltered according to others (Callinan et al., 2010; Lee et al., 2011). As regards inequalities in smoking, there is weak evidence to show that workplace smoking restrictions may be more effective for higher educational groups, but at a population level the effect of clean indoor air laws on smoking cessation does not vary with socio-economic position (Brown et al., 2014; Hill et al., 2014), though only a small number of studies have been undertaken. With the aim of increasing the amount of empirical evidence, this study assessed the effect of both types of smoking-control measures in smoking cessation in different socio-economic groups in Spain. The first regulation in Spain that sought to control smoking through taxation was introduced in 1992, since when tobacco prices have risen considerably. In addition, Spain promulgated the 2006 Smokefree Act, thus becoming one of the first European countries to implement this type of measure which banned smoking in workplaces, bars and restaurants. The impact of nationwide tobacco control policies on smoking behaviour should preferably be examined in a longitudinal study design, wherein information about smoking behaviour before and after the implementation of a policy is measured. Unfortunately, longitudinal data on smoking are rare. In most of the cases alternative approaches are used to obtain evidence on the potential impact of national policies on smoking. For example, the use of estimates on smoking behaviour based on crosssectional studies of several years. A natural experiment was thus undertaken, using data on smoking drawn from a series of national interview surveys conducted over the course of the two decades since 1992. Specifically, the aim of this study was to evaluate the effect of tobacco prices and the implementation of smoke-free legislation on the smoking cessation, by educational level, across the period 1993–2012. Methods The data were drawn from eight Spanish National Health Surveys conducted over the course of the preceding twenty years, i.e., 1993, 1995, 1997, 2001, 2003–2004, 2006–2007, 2009–2010, and 2011–2012. Subjects were selected by means of a stratified multi-stage sampling strategy and information was collected through personal interviews at subjects’ homes. A more detailed outline of the methodology used in these surveys can be found elsewhere (MSSSI, 2015). The sampling framework was made up of the Spanish non-institutionalised population aged 16 or over. First the towns were chosen by random selection proportional to the size of the population, and then the census areas households in each section were chosen by simple random selection. Individual households were subsequently selected by simple random selection, and one adult aged 16 or over was selected in each household. Information on tobacco consumption was included in the questionnaire. Specifically, in answer to the item, ‘‘Could you
please state whether you smoke’’, interviewees were asked to choose one of the following possible replies: (1) Yes, I smoke daily; (2) Yes, I smoke, though not daily; (3) No, I do not smoke but I used to; or, (4) No, I do not smoke now and have never routinely smoked. For study purposes, we only included subjects who were smokers, daily and non-daily, or ex-smokers at the date of the interview. The smoking cessation quit-ratio was defined as the ratio of former smokers to ever smokers. Educational level was used as the indicator of socio-economic position: this variable referred to the highest level of education attained and was grouped into the following two categories: lower secondary education or less; and upper secondary education or higher. The quit-ratio estimates were computed for the group aged 25–64 years. The age of 25 years was chosen as the lower limit because persons of this age would most likely have attained their highest level of education. Similarly, the age of 64 years was chosen as the upper limit to avoid imprecise estimates in women aged over 64 years because, until 2003, less than 5% of Spanish women in this age group had smoked at some time in their lives. The annual trend in tobacco prices in Spain for the period 1993– 2012 was obtained from the consumer price index, published by the National Institute of Statistics (Instituto Nacional de Estadı´stica, 2014). In order to use the real price of tobacco, the annual tobacco prices were adjusted for inflation. The quit ratio was the indicator of smoking cessation used. This measure is frequently used to assess progress of comprehensive tobacco control programs, as in the United States where the ratio of former smokers to ever smokers for each survey year is obtained (Agaku, King, & Dube, 2014). Nevertheless, changes in quit ratio can be driven by population changes other than cessation (e.g., differing mortality rates among current/former smokers). The present analysis has been limited to the adult population aged 25– 64 years, therefore it has been excluded the possibility of mortality bias among older smokers. The age-standardised quit ratio was estimated for each study period, taking the 1993 ever-smoker population as standard. By using the method of direct standardization, in each educational level the age-specific quit ratios were weighted by standard population in each age. Although eight National Health Surveys were analysed, the quit ratios were calculated for 12 periods. The interviews in the first four National Health Surveys were conducted over a period of two weeks, and so a single quit-ratio estimate was computed for 1993, 1995, 1997 and 2001, respectively. However, since the interviews in the last four National Health Surveys were distributed over twelve months, i.e., from April of one year to March of the next (2003–2004 and 2009–2010) or from July of one year to June of the next (2006– 2007 and 2011–2012), in each of these cases, we computed two quit-ratio estimates: one based on the interviews conducted in the first six months; and another based on the interviews conducted in the last six months. We thus obtained eight estimates deemed to correspond to the years 2003, 2004, 2006, 2007, 2009, 2010, 2011 and 2012, respectively. Separate analyses of regression were performed for men and women. Given the change in survey duration (2 weeks versus 12 months), the measurements in the period after 2003–2004 will be characterized by greater error variance and perhaps correlation between the error terms of neighbouring time points. The Durbin– Watson statistic for serial autocorrelation of the error terms in the regression models was calculated (Wagner, Soumerai, Zhang, & Ross-Degnan, 2002). No evidence of autocorrelation was detected because values were closed to 2. In each category of educational level, the relationship between tobacco prices and the quit ratio was analysed using linear regression. Because of that relationship may be a reflection of the smoking epidemic, the analysis was adjusted for time as it has been
Please cite this article in press as: Regidor, E., et al. Impact of tobacco prices and smoke-free policy on smoking cessation, by gender and educational group: Spain, 1993–2012. International Journal of Drug Policy (2015), http://dx.doi.org/10.1016/j.drugpo.2015.05.011
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done in other previous studies (Agaku et al., 2014; Bosdriesz, Willemsen, Stronks, & Kunst, 2015). In view of the fact that previous studies in Spain and in Ireland reported that smoking trends had changed substantially after the introduction of smokefree legislation (Brugha et al., 2009; Regidor et al., 2011), this relationship was addressed in two ways: firstly, by focusing on the period preceding the introduction of comprehensive smoke-free legislation in January 2006; and secondly, the relationship between tobacco prices and the quit ratio was calculated for the entire study period, adjusted for trend and the presence or absence of the law. To reflect the absence or presence of the law, we created a dichotomous variable whose value was 0 in the years preceding the implementation of the Smoke-free Act and 1 in 2006 and subsequent years. The introduction of smoke-free legislation was then evaluated. A segmented regression analysis was performed to assess whether there had been a change in quit-ratio levels and/or trends between the pre- and post-intervention periods. Segmented regression analysis is a quasi-experimental approach for evaluating longitudinal effects of interventions (Sanson-Fisher, D’Este, Carey, Noble, & Paul, 2013; Wagner et al., 2002). The analysis involves fittings an interrupted time series to the data. A time series is fit pre- and postintervention using a disjointed segmented linear regression model. Each segment of the series is allowed to exhibit both level and a trend. Segmented regression analysis makes it possible to estimate changes in level and trend associated with the intervention, controlling for baseline level and trend. A change in level, e.g. a jump or drop in the outcome after the intervention, constitutes an abrupt intervention effect. A change in trend is defined by an increase or decrease in the slope of segment after the intervention as compared with the segment preceding the intervention. The model used was the next: QRt ¼ b0 þ b1 time þ b2 intervention þ b3 time after intervention þ et ; where QRt is the quit ratio in year t; time is a continuous variable indicating time in any year at time t from the start of the study period; intervention is an indicator of time t occurring before (intervention = 0) or after (intervention = 1) the introduction of smoke-free legislation; and time after intervention is a continuous variable that counts the number of years after the intervention at time t, denoted 0 for the period preceding the introduction of smokefree legislation. In the model, b0 estimates the baseline level of the outcome, the quit ratio, at time zero; b1 estimates changes in the quit ratio that occurred in each year before the intervention (i.e., the baseline trend); b2 estimates changes in the quit-ratio level that
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occurred immediately after the intervention, i.e., from the end of the preceding segment; and b3 estimates post- versus pre-intervention changes in trend in the quit ratio. The error term et at time t represents random variability not explained by the model. Finally, the effect of smoke-free legislation was also estimated by the elaboration of a counterfactual scenario to answer the question: what would have been the value of the quit ratio at the end of the study period in the absence of intervention? To do this, apart from calculating the predicted value of the ratio quit in 2012 using the model based on intervention, the predicted value was also calculated using the model based on baseline level and time only, as if the intervention had not occurred (counterfactual scenario). Results The trend in tobacco prices and the absence or presence of a smoke-free law in the study period can be seen in Table 1. From 1993 to 2003 tobacco price increased by 50% and in the two decades covered by this study, the price multiplied by 2.5. Table 1 also shows the sample size along with the quit ratio in men and women at each of the observation points. The trend in tobacco prices and that of the quit ratios in subjects having low and high educational levels are shown in Fig. 1. The relationship between tobacco prices and the quit ratio is shown in Table 2. In the period prior to the implementation of smoke-free legislation, no significant relationship was observed between tobacco prices and the quit ratio in either of the two categories of educational level after adjusting for time. When the entire study period was analysed, no significant relationship was in evidence, except among women with a low educational level. In this group, the increase in tobacco prices was associated with a fall in the quit ratio (regression coefficient: 0.089; p = 0.002). The results of the assessment of the impact of the smoke-free law on the quit ratio can be seen in Table 3 and Fig. 2. Before the law’s introduction, the quit ratio displayed an upward trend in both men and women with low and high educational levels. The b1 coefficient of the baseline trend was significant in all four groups. Following the introduction of the law, the quit ratio increased in all groups, though the magnitude of this increase was greater in women than in men. The coefficient that measured the change in quit-ratio level after the intervention as compared with the quit-ratio level preceding the intervention only was statistically significant in women with a low educational level (b2 = 4.66; p < 0.001). After the law’s introduction, a change was observed in the trend among men with a low educational level and women in both educational groups. The regression coefficient was significant in men (b3 = 0.79; p = 0.023) and in women (b3 = 0.83; p = 0.009) with a low educational level;
Table 1 Tobacco price index, absence or presence of smoke free-law, and number of smokers and former smokers in the sample and quit ratio in men and women by year. Spain 1993– 2012. Year
Tobacco prix index
Smoke-free law
Sample size of smokers and former smokers (n) and quit ratio (%) and standard error (SE) Women
Men
1993 1995 1997 2001 2003 2004 2006 2007 2009 2010 2011 2012
100.0 112.2 132.8 143.0 151.8 156.7 158.2 167.1 186.2 210.4 230.9 241.8
No No No No No No Yes Yes Yes Yes Yes Yes
n
Quit ratio
SE
n
Quit ratio
SE
4840 1451 1450 4719 2409 2256 3761 2961 2547 2252 2288 2105
26.4 29.2 29.7 31.4 34.3 34.4 38.6 39.5 37.5 38.9 39.2 41.9
0.6 1.2 1.2 0.7 1.0 1.0 0.8 0.9 1.0 1.0 1.0 1.1
2262 774 853 3058 1548 1639 2547 2017 1849 1732 1720 1555
23.3 22.7 24.6 27.6 32.8 31.1 36.8 37.6 36.0 41.5 36.5 36.4
0.9 1.5 1.5 0.8 1.2 1.1 1.0 1.1 1.1 1.2 1.2 1.2
Please cite this article in press as: Regidor, E., et al. Impact of tobacco prices and smoke-free policy on smoking cessation, by gender and educational group: Spain, 1993–2012. International Journal of Drug Policy (2015), http://dx.doi.org/10.1016/j.drugpo.2015.05.011
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4
Men
Women
50
50
300
35
100
10
50
Prices index
2007
2006
2005
2004
2003
2002
2001
2000
1999
1998
1997
1996
1995
1993
0
2012
2011
2010
2009
2008
2007
2006
2005
2004
2003
2002
2001
2000
1999
1998
1997
1996
1995
50
0
0
1994
Quit ratio Prices index
5
0
1993
100
15
2012
Quit ratio
5
150
1994
10
25 20
2011
15
200
2010
150
20
Low
30
2009
25
Quit ratio %
Low
30
Prices index
200
2008
35
250
High
40
Prices index
250
High
40
Quit ratio %
300
45
45
Fig. 1. Age-standardized quit ratios by educational level and sex and tobacco prices.
Table 2 Parameter estimates and p-values from regression models evaluating the effect the tobacco prix on quit ratio (%) in Spain for the period 1993–2004 and for the period 1993– 2012. Low education
Period 1993–2004 (adjusting for time) Beta for men Beta for Women Period 1993–2012 (adjusting for time and presence/absence of the law) Men Beta (adjusting for time) Beta (adjusting for time plus presence/absence of the law) Women Beta (adjusting for time) Beta (adjusting for time plus presence/absence of the law)
High education
Coefficient
p value
Coefficient
p value
0.056 0.050
0.492 0.680
0.081 0.069
0.506 0.824
0.060 0.060
0.093 0.116
0.004 0.001
0.923 0.982
0.094 0.089
0.004 0.002
0.106 0.106
0.099 0.123
Table 3 Parameter estimates and p-values from segmented regression models predicting annual quit ratio (%) in Spain for the period 1993–2012. Low education
High education
Coefficient
p-value
Coefficient
p-value
Men Intercept b0 Baseline trend b1 Level change after law b2 Trend change after law b3
22.76 0.71 1.93 0.79
0.000 0.001 0.264 0.023
27.42 0.67 1.40 0.02
0.000 0.007 0.540 0.956
Women Intercept b0 Baseline trend b1 Level change after law b2 Trend change after law b3
21.48 0.51 4.66 0.83
0.000 0.002 0.001 0.009
23.07 1.17 3.10 1.19
0.000 0.003 0.365 0.082
among women with a high educational level, it bordered on statistical significance (b3 = 1.19; p = 0.082). The sum of b1 coefficient of the baseline trend and b3 coefficient of trend change after law would be the actual value of the new trend in the postintervention segment. The new trend was no significant: in men and women with a low educational level the value was 0.08 (p = 0.880) and 0.32 (p = 0.230), and in men and women with a high educational level the value was 0.69 (p = 0.126) and 0.02 (p = 0.968), respectively. Table 4 shows that, based on the intervention, the predicted value of the quit ratio in 2012 is lower than it would be if the intervention had not occurred, except in men with a high educational level among whom both values display a similar magnitude.
Discussion Main findings Prior to the introduction of the smoke-free law, the tobacco prices and the magnitude of the quit ratios showed an upward trend, but there was no evidence of relationship between tobacco prices and quit ratios in any of the groups studied after adjusting for time. Analysis of the entire study period showed similar results, and even a decrease in the percentage of smokers quitting among women with a low educational level. The smoke-free law not only altered the smoking pattern in the short term, but also altered preexisting trends. Whereas quit ratios rose in all groups shortly after the ban, they declined in the following years, except among men
Please cite this article in press as: Regidor, E., et al. Impact of tobacco prices and smoke-free policy on smoking cessation, by gender and educational group: Spain, 1993–2012. International Journal of Drug Policy (2015), http://dx.doi.org/10.1016/j.drugpo.2015.05.011
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Fig. 2. Age-standardized quit ratios by educational level and sex. The triangles represent subjects with low education and the diamonds represent subjects with high education. The dashed line represents the estimated data based on the segmented regression analysis.
Table 4 Estimated values for the quit ratio in percentage (and standard error) in 2012 based on the intervention (segmented regression) and on the counterfactual value (baseline level and trend only). Spain for the period 1993–2012.
Men Yˆ2012 Yˆ2012
(with law) =
Women Yˆ2012 (with Yˆ2012
b0 + b1 * 20 + b2 * 1 + b3 * 7 b0 + b1 * 20
(without law) =
law) =
b0 + b1 * 20 + b2 * 1 + b3 * 7 b0 + b1 * 20
(without law) =
Low education
High education
33.3 (0.9)
42.3 (1.3)
35.1 (0.8)
42.3 (0.8)
30.5 (0.8)
41.1 (1.9)
32.5 (0.9)
43.8 (1.4)
with a high educational level. In the long term, the magnitude of the quit ratio was lower in the presence of the law than in the counterfactual scenario which postulated its absence, once again with the single exception of men with a high educational level. Comparison with other studies and possible explanations A considerable number of studies have found that tobacco prices display an independent association with decreased consumption among smokers (Chaloupka & Warner, 2000; IARC, 2011; Levy, Chaloupka, & Gitchell, 2004). There are fewer studies however that address the relationship between price and definitive smoking cessation. Although some studies on young adults report a relationship between an increase in price and an increase in quit attempts, there is less evidence to show that raising tobacco prices is successful in terms of maintaining smoking cessation (Rice, Godfrey, Slack, Sowden, & Worthy, 2009). There is still less evidence regarding the relationship between tobacco prices and smoking cessation by reference to ever smokers’ socio-economic position. A study undertaken in the Netherlands reported that exposure to a price increase was not significantly associated with increased odds of quit attempts or successful smoking cessation in any socio-economic group (Nagelhout et al., 2013). In the present study the tobacco price was not associated with smoking cessation in most of the groups analysed. Even, among women with a low educational level, the relationship observed for the entire study period was contrary to expectations, because the quit ratio, rather than rising, fell with the increase in the price. This finding is probably due to the change in smoking patterns caused by the introduction of the Smokefree Act, in view of the fact that, in the years preceding the
implementation of this law, no relationship had been observed between the price of tobacco and quit ratios in any of the four groups analysed. The increase in quit ratios observed in Spain in the period immediately following the introduction of smoke-free legislation has also been observed in Scotland (Fowkes, Stewart, Fowkes, Amos, & Price, 2008) and England (Hackshaw, McEwen, West, & Bauld, 2010). Neither of these studies found any evidence of a differential impact depending on the socio-economic position of smokers in this immediate period. In the Netherlands too, a small effect of smoke-free legislation on quit attempts was observed in the period immediately following the law’s implementation but there were no educational differences in such attempts (Nagelhout et al., 2013). Only one study, undertaken in Italy, where the smoking ban in public places was absolute, has assessed the short- and long-term impact of smoke-free legislation on smoking habit by reference to the socio-economic position of individuals (Federico, Mackenbach, Eikemo, & Kunst, 2012). As in Spain, a sudden increase in the quit ratio was observed following the law’s introduction, whereas the quit ratio fell as post-legislation. In the case of persons with a high educational level, however, long-term trends differed: in Italy, the quit ratio fell in men and rose in women, whereas in Spain it remained stable in men and fell in women. The Italian findings agree with our counterfactual scenario (i.e., without the presence of the smoke-free law) where, in the long term, the magnitude of the quit ratio would have been more favourable for most of the groups studied. It is unlikely that the observed decrease in the quit ratio in most of the groups, after the smoke-free law, came about as a consequence of more subjects taking up smoking. In view of the age range of the study population (25–64 years), this finding is fundamentally due to relapses of former smokers who resume smoking. The authors of the study conducted in Italy indicated a possible relaxation in complying with the ban in work and public places. Yet, the results regarding this law’s effectiveness in Spain suggest that this has not been the case. Moreover, a trend in smoking behaviour similar to that reported in Italy and Spain has also been observed in Ireland. Probably, after the implementation of smoke-free legislation many people decided to give up smoking, increasing the number of ex-smokers, but some months later some of these smokers who got quitting returned to smoking. Since smoking cessation coincided in many smokers as a result of the law, the relapse that occurs in some smokers in the months
Please cite this article in press as: Regidor, E., et al. Impact of tobacco prices and smoke-free policy on smoking cessation, by gender and educational group: Spain, 1993–2012. International Journal of Drug Policy (2015), http://dx.doi.org/10.1016/j.drugpo.2015.05.011
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following the quit, due to withdrawal syndrome, it is expected that also affects many individuals. In any case, it cannot be excluded that other developments have affected the long-term decrease in quit ratios in Spain, such as ‘‘ceiling effects’’ if incremental changes in quit ratios tend to be smaller at higher levels or the continuing economic crisis. Study strengths and limitations One of the largest effects of tobacco price increases is to reduce the initiation of smoking initiation among youth. However, in the present study smoking initiation was not studied because educational level was used and people lower than under 25 years of age have less likely of attaining their highest level of education as people older. In any case, although changes in smoking cessation are, in addition to changes in smoking initiation, one of the mechanisms through which the smoking epidemic evolves, some authors have pointed that in later stages of the smoking epidemic, quitting smoking can make important may contribute to differences in smoking prevalence (Schaap et al., 2008). Other measures of smoking behaviour also could have been used (attempts quit, cigarettes per day). However, the attempts quit do not appear properly collected in all health surveys and estimates on the number of cigarettes per day from surveys are imprecise. In fact, some authors and national and international institutions use sales figures for monitoring the number of consumed cigarettes (Ferna´ndez et al., 2004; MSSSI, 2014a). Based on representative samples of the Spanish population, 12 quit-ratio estimates were obtained across a period of two decades, making it possible to perform segmented regression analysis of interrupted time series to control for prior trends, and to study the dynamics of change in quit ratios following the introduction of smoke-free legislation. However the study actually has statistical low power due to the small number of observations. For example, the finding of no significant relationships of price with quit ratio in the period before the Smoke-free Act could be due to the low power. The relationship between the price and the consumption of tobacco in Spain has been evaluated in two studies that found that a rise in real price of tobacco is associated with a decrease in cigarette consumption and an increase in smoking cessation (Ferna´ndez et al., 2004; Lo´pez Nicola´s, 2004). These studies used, respectively, tobacco official sales for the period 1965–2000 (Ferna´ndez et al., 2004) and data from national health surveys from 1995 to 1997 (Lo´pez Nicola´s, 2004). Probably the different findings with respect to those obtained in the present study are due to the different variables of smoking behaviour used. While Ferna´ndez et al. (2004) investigated the annual per capita cigarette consumption, Lo´pez Nicola´s (2004) investigated the duration up to quitting. According some studies that have evaluated the price responsiveness by age, the tobacco use among young people fall more in response to a price increase than the tobacco use among older people (Levy et al., 2004; Thomas et al., 2008). In the present study we performed a sensitivity analysis by selecting only young adults 25–44 years and the findings were similar: lack of relationship between increase in tobacco prices and quit ratio in all groups, except among women with a low educational level. In this group the regression coefficient for the entire study period, adjusted for trend and the presence or absence of the law was 0.10 (p = 0.027). The strategy used in this study was to perform estimates into four groups based on sex and educational level. Segmented regression aggregates subject according those individual variables by time point but does not allow for control of other individuallevel covariates. Quit ratios were higher in unemployed than in
unemployed persons (MSSSI, 2014b). Although the decrease in the magnitude of the quit ratio after the introduction of the smoke-free law may possibly have been due to the rise in unemployment brought about by the 2008 economic crisis, when the quit ratio was analysed in employed and unemployed persons from 2006 to 2012, the trend in both groups were similar to those among all Spanish men and women, respectively (data not shown). The 2006 Smoke-free Act banned smoking in all public and workplaces, with some exceptions in hospitality venues (no ban on venues of less than 100 m2, and ‘‘smoking areas’’ were allowed in venues over 100 m2). In January 2011, a new law was enacted (Ley 42/2010, de 30 de diciembre). The new smoking law amended the previous law by banning smoking in all places that had formerly been deemed an exception. Even so, previous studies have shown that the 2006 Act was effective, in that its implementation was followed by a decrease in second-hand smoke exposure, both at the workplace and among non-smokers during leisure time (Sureda et al., 2014). Although the quit ratio is frequently used to assess tobacco control policies (Agaku et al., 2014; Bosdriesz et al., 2015; Federico et al., 2012), it is a proxy of cessation rate because does not take into account age at starting and time since quit smoking. Therefore, the quit ratio may not be adequate to evaluate the effect of price or any other policy instrument of tobacco control implemented in a year, as the quit ratio includes smokers who quit smoking before that year and remained non-smokers since. Under the assumption that the study population is the same source population before and after the intervention, the quit ratio is able to detect changes in smoking cessation over the two periods, but it not sensitive to the exact timing of the occurrence of change. Conclusion This study’s findings do not support a clear relationship between tobacco prices and quit ratio in national populations in the study period. Moreover, we found that after the implementation of smoke-free legislation in Spain the trend in the quit ratio in most of the socio-economic groups studied was different from the trend observed before implementation. In view of the fact that there was a difference between the trends observed for men and women with a high educational level, the law’s implementation cannot be said to have widened or narrowed existing inequalities in the quit ratio. The smoke-free policies benefit the lower socioeconomic groups by the intended effect of decreasing exposure to environmental tobacco smoke, but they do not seem to affect inequalities in smoking. Funding This work was carried out by the project ‘‘Tackling socioeconomic inequalities in smoking: learning from natural experiments by time trend analyses and cross-national comparison (SILNE)’’, which is funded by the European Commission, Directorate-General for Research and Innovation, under the FP7-Health-2011 program, with grant agreement 278273. Competing interests The authors declare that they have no conflicts of interest. References Agaku, I. T., King, B. A., & Dube, D. (2014). Current cigarette smoking among adults – United States, 2005–2012. Mortality and Morbidity Weekly Report, 63, 29–34. Becker, G. S., Grossman, M., & Murphy, K. M. (1994). An empirical analysis of cigarette addiction. American Economic Review, 84, 396–418.
Please cite this article in press as: Regidor, E., et al. Impact of tobacco prices and smoke-free policy on smoking cessation, by gender and educational group: Spain, 1993–2012. International Journal of Drug Policy (2015), http://dx.doi.org/10.1016/j.drugpo.2015.05.011
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